Put both sum=0 and denom=1 just after this line ..while (toupper(answer)=='Y')
Or else if we try to calculate the series another time, it will give wrong answer.

2. Floating Point error

I tried lots of tricks on the code.. and found that actually denom = factorial (count) is going out of range beyond count=7
Factorial(7) = 5040
Factorial(8) = 40,320 ( more than 32,768 )
So the program incorrectly shows Negative values of denom beyond 7. You start calculating incorrect sum beyond 7
At around count=18, the value of denom is shown 0. So you get the error.